Synthesis, Characterization, and Anticancer Activity of Pyrene-Based Schiff Base Ligands and Their Transition Metal Complexes

This study details the synthesis, characterization of unsymmetrical Schiff base ligand and their metal complexes Ni(II), Zn(II), Pb(II), and Cu(II) for anticancer assessment. These ligands were prepared by condensation reaction between 1,2-phenylenediamine in combinations with 2,5-dihydroxybenzaldehyde, 1-pyrenecarboxaldehyde, and 3-hydroxybenzaldehyde, producing distinctive molecular structures. Comprehensive analysis of their structural and electronic properties were conducted using elemental analysis, UV–Vis, FT-IR. 1H NMR, 13C-NMR spectroscopy, supplemented by magnetic moment measurements and fluorescence studies. The biological efficacy of the Schiff base derivatives was tested against DLD1 colon cancer cells, with cellular imaging employed to observe their effects. Notably, cytotoxicity assays showed IC50 values of 38.4 µM for ligand L1′and 7.3 µM for ligand L2′, indicating strong activity against colorectal carcinoma (CRC) cells. Significantly, both compounds exhibited minimal toxicity toward healthy epithelial cells (IC50 > 200 µM), demonstrating their selective anticancer potential.